DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 16

• Manufacturer Part Number: DS2480
• Description: Serial 1.Wire Line Driver
• Manufacturer: Dallas Semiconducotr

Certain applications may require a duration for a strong
pull–up or programming pulse that cannot be realized
using one of the predefined values. Selecting infinite
duration allows the host to generate pulses of any
length. As a consequence, however, the host becomes
responsible to actively control the duration of the pulse.
Failing to do so may require a power–on reset or master
reset cycle of the DS2480. For this reason, infinite dura-
tion should only be used if absolutely necessary.
STRONG PULL–UP TO 5V, INFINITE DURATION Figure 7c
As before, processing the command is essentially the
same, regardless if it is for a strong pull–up or a pro-
gramming pulse. At t
command byte. At t
mand and immediately activates the strong pull–up or
switches in the 12V programming voltage. To end the
pulse, the DS2480 must receive a termination com-
mand, code F1h, which occurs at t
command does not generate a response byte. The
12V PROGRAMMING PULSE, INFINITE DURATION Figure 7d
DS2480
042498 16/26
12V
5V
0V
5V
0V
END OF PREVIOUS
END OF PREVIOUS
TIME SLOT
TIME SLOT
2
the DS2480 has received the com-
1
the host starts sending the pulse
t
1
t
1
TIME
IDLE
TIME
IDLE
t
2
3
t
2
. The termination
STRONG PULL–UP ON
PROGRAMMING VOLTAGE
STEEP SLOPES
IS APPLIED
The time to end a pulse of infinite duration strongly
depends on the baud rate of the communication
between host and DS2480. Neglecting the response
time of the host, the minimum pulse durations are:
86.8 s at 115.2 kbps, 173.6 s at 57.6 kbps, 520 s at
19.2 kbps and 1.04 ms at 9.6 kbps.
DS2480 will immediately end the pulse and send out the
response byte of the pulse command. The idle time
between t
the command byte at the selected baud rate. The idle
time between t
mit the pulse response byte, plus the response time of
the host plus the time to transmit the command and/or
data to generate the next time slot.
1
and t
t
t
3
3
3
and t
2
is determined by the time to transmit
TIME
TIME
IDLE
IDLE
4
is comprised of the time to trans-
t
4
t
4
BEGIN OF NEXT
BEGIN OF NEXT
TIME SLOT
TIME SLOT